Child pedestrians' crossing gap thresholds1

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Abstract

Three gender-balanced groups of 16 school children (5–6 years, 8–9 years, 11–12 years) participated in individual pretests of vision, hearing, and time to walk across a 12-m wide urban street and back. Each child then completed 10 roadside trials requiring judgement of the threshold point at which they would no longer cross in front of traffic approaching from their right. The judgements were made from a site immediately in front of a parked car at a point 2 m from the kerb and 4 m from the centre of the road. Traffic speeds and distances were measured using a laser speed and distance detector. The results indicated that, overall, distance gap thresholds remained constant regardless of vehicle approach speeds. Analysis of the thresholds for distance gap judgements for the 4-m half-street crossing showed that some of the older children could be expected to make safe decisions, but this was not so for the 5–6- and 8–9-year-olds at vehicle approach speeds above 60 kph. Almost two-thirds of the children reported using distance to judge gaps, which proved the least adequate strategy in terms of proportion of resultant safe decisions. The findings are discussed in relation to developing effective child pedestrian safety strategies.

Introduction

International road accident statistics clearly show that young child pedestrians are at high risk of death or injury. British data reveal that children aged 5–7 years are most at risk (Howarth et al., 1974, cited in Malek et al., 1990), while in New Zealand (Roberts, 1994), the United States (Malek et al., 1990) and Canada (Jonah and Engel, 1983) child pedestrian accidents peak between the ages of 5 and 9 years, coinciding with the early elementary school years. Most pedestrian accidents in New Zealand occur between 8.00 and 9.00 a.m. and between 3.00 and 4.00 p.m. (Land Transport Safety Authority, 1992), which coincide with the times at which children walk to and from school. The pattern of school-age children's pedestrian casualties also follows that of the school year, with rates falling during periods of school closure for vacations (Jones and Nguyen, 1988). Casualty patterns are such that injury and fatality rates for boys typically are significantly higher than those for girls, and injuries suffered were found to be most severe between the ages of 5 and 9 years (Jones and Nguyen, 1988). Vehicle speed contributes significantly to the severity of child pedestrians' injuries, particularly at speeds above 50 kph (Pitt et al., 1990).

Child education programmes are the most common approach to prevention (Malek et al., 1990; Roberts, 1994) and there is wide acceptance of the value and necessity of teaching pedestrian skills (Christoffel et al., 1986; Demetre et al., 1993; Grayson, 1981; Malek et al., 1990; Yeaton and Bailey, 1978; Young and Lee, 1987). However, the findings reported in these studies show that, while education improves knowledge as measured by verbal report and/or observed behaviour, very few programmes have produced evidence that the training is either durable or that it has reduced child pedestrian casualty rates. Teaching children safe road crossing appeals as an active form of safety intervention. However, given the findings on its efficacy, it may instead provide parents and children with a false sense of confidence in the young child pedestrian's competence and safety. For example, it is believed that specific cognitive developmental limitations may impose constraints on what young children can learn and do in traffic environments, which also increases their accident risk (Embry and Malfetti, 1981; Sandels, 1975, cited in Michon, 1981; Shinar, 1978; Vinje, 1981).

These views fit Piaget's theory of cognitive development regarding children in the preoperational stage (circa ages 5–7 years). Piagetian models of children's cognitive processes have been critically assessed in recent times and need to be viewed with some caution (Gelman and Baillargeon, 1983; Kuhn, 1988; Lee et al., 1984; Parsonson and Naughton, 1988). Alternative explanations, such as lack of critical experience or competencies, may be more valid. For example, a young child's view and perception of oncoming traffic may be affected by their height restricting their range of view, resulting in less than optimal surveying of traffic from behind a parked car or when obstructed by utility poles, trees, or buildings. Perception of a vehicle's change in apparent size as it approaches may also be affected by the view provided from a child's height. Visual attention studies report that younger children are more easily distracted by task-irrelevant events, less able to sustain attention, and less efficient at searching their visual field (Akhtar and Enns, 1989; Malek et al., 1990; Shinar, 1978).

Children also may have more difficulty in judging speed and distances than adults. Laboratory studies by Siegler and Richards (1979)indicate that the concepts of time, speed and distance undergo a lengthy developmental sequence. Five-year-old children in their study did not clearly discriminate the concepts of time, speed and distance, and marked confusion existed among the three concepts for 8- and 11-year-old children, with many of the latter using distance to judge time, which appeared to be the last concept mastered. With respect to distance judgements, both Shinar (1978)and Vinje (1981)report children's judgements as less accurate and more variable than those of adults. These findings point to perceptual, as well as cognitive, developmental processes affecting children's judgements.

Safe crossing decisions may require accurate judgement of a vehicle's time-to-impact, distance and speed. As noted above, it has been suggested that the perceptual and cognitive functioning necessary to make such decisions may exceed young children's developmental capacity. However, adults seem also to have difficulty in coping with such judgements, tending primarily to rely on distance. Studies of speed and safe gap estimation by drivers show that the time gaps they accept systematically reduce as vehicle approach speeds increase, with males typically accepting smaller gaps than females (Hills, 1980; Hills and Johnson, 1980, cited in Hills, 1980; Parsonson et al., 1996). On average, drivers' judgements of `last safe moment to cross' occurred at almost constant distances, regardless of vehicle approach speeds (Hills, 1980; Parsonson et al., 1996). Thus, it appears that concurrent estimation of both speed and distance is too complex even for experienced adults. Accordingly, failure to do so by children is not necessarily solely attributable to a lack of cognitive development.

Findings on the traffic approach speed judgements of child pedestrians are conflicting. Children aged as young as 5 years have been deemed incapable of safely judging the speed of oncoming cars, as it is believed that they tend to overestimate approach speeds (Salvatore, 1973, cited in Vinje, 1981). Unobtrusive observations tend to support this, revealing that children aged about 5 years accept a larger safety margin than older children (Van der Molen, 1977, 1981, cited in Vinje, 1981). Conversely, younger pedestrians may more frequently make risky gap acceptances (Harrell and Bereska, 1992). The assumption that the younger children are judging vehicle speed effectively needs to be better investigated. For instance, it is possible that the children in the studies cited by Vinje (1981)were making conservative distance judgements, and thus appearing to make safe speed judgements. Given that the research with drivers noted above shows that they are not good judges of vehicle approach speeds, but rely instead on distance, it is unlikely that young children would prove more effective judges of speed.

This view is supported by a number of studies. For example, Salvatore (1974, cited in Shinar, 1978) had children estimate the speed of approaching cars as fast, medium, or slow, and found that accuracy of estimates improved with age for vehicles travelling at slow and medium speeds, but that it decreased with age for fast-moving cars. This suggests that younger children's judgements were more conservative and that they may have relied on setting longer distance gaps than older children, or may have responded to educational rather than sensory cues. To overcome the problems associated with the broad categories of fast, medium, or slow, Hoffmann et al. (1980)had children in different age groups view a series of film clips of vehicles approaching them at four different speeds, estimating the time the vehicle would take to reach them. All groups underestimated time-to-arrival, but underestimation decreased with age and approximated adult performance by 12 years of age.

In contrast, studies using a simulated road crossing (Lee et al., 1984; Young and Lee, 1987; Demetre et al., 1992, Demetre et al., 1993) found children overcautious when making crossing decisions, but that, following training, children aged as young as 5 years made sensible traffic gap decisions (Demetre et al., 1993; Young and Lee, 1987). Results from the latter two studies show that the effect of training was initially to improve aspects of children's road-crossing skill, but Demetre et al. (1993)found that by a 3-month follow-up, differences between the trained children and controls had washed out. Initially promising, but transitory, training and generalisation effects also have been found in studies training young children to cross actual streets (Mohr et al., 1983; Yeaton and Bailey, 1978), although Yeaton and Bailey (1978)found that retraining after 1 year tended to re-establish children's crossing skills which had fallen below a satisfactory level in the intervening period.

The equivocal results from the various studies on young children's ability either to judge approaching vehicles' speed, distance, or time-to-impact, or reliably and durably to learn to make safe crossing decisions, mean that it is difficult to reach firm conclusions about either children's gap-judging ability or the relationship between vehicle approach speed and their gap judgements. However, the findings do suggest the possibility that younger children may be the most conservative in setting distance gaps when making crossing decisions.

In a preliminary study investigating the thresholds of gap acceptance of four young children (7–9 years) under conditions approximating normal street-crossing decision-making, Connelly et al. (1996)reported that distance, rather than an approaching vehicle's speed, was the primary factor in determining gap acceptance thresholds. Vehicle approach speeds of 20, 30 and 50 kph were used in accordance with a random schedule and the children, standing at the kerb, indicated the moment at which they would no longer cross the street in front of the approaching vehicle. The time gaps obtained from these judgements revealed that all four children consistently allowed smaller safety thresholds as the speed of approaching vehicles increased. They also showed that three of the four children often selected potentially dangerous gaps, especially at vehicle approach speeds exceeding 20 kph.

In order to determine the generality of the findings of the above pilot study, a further, more extensive, investigation of children's safety gap thresholds, with a larger sample of children and under more natural traffic flow and traffic speed conditions, was undertaken.

Section snippets

Subjects

Forty-eight children participated, comprising 8 boys and 8 girls in each of three age groups, 5–6 years, 8–9 years and 11–12 years. All children were recruited through schools, with parents providing informed consent for their child's participation. Given the small sample, no attempt was made to match the three groups on socio-economic or ethnic variables.

Setting

An urban street, sited near the contributing schools, with an average daily traffic flow of 6 620 vehicles (Traffic Flow Data, Hamilton City

Prescreening

Most children produced what the Keystone Vision Screener manual (Mast/Keystone Inc., 1993) identified as `acceptable' levels of performance on the visual screening tests. All heard all audiometer test frequencies at the two presentation levels.

Road crossing

The timing of the two road-crossing trials produced data equivalent to four trials of crossing the 4 m to the centre of the road. These data were averaged to give mean road-crossing times for each age group and show an age-related pattern, with the

Discussion

In summary, the present findings reveal that pre-adolescent school-age children, particularly those aged below 10 years, have relatively poor skills at reliably setting safe distance gap thresholds, and thus do not consistently make safe crossing decisions. Their capacity for making such decisions safely progressively declines as vehicle approach speeds exceed 55 kph. The results also indicate that the children primarily relied upon distance in making judgements of safe street crossing gaps,

Acknowledgements

A grant from the New Zealand Lotteries Grants Board funded the purchase of the laser speed and distance recorder used in the study.

References (31)

  • K Ampofo-Boatang et al.

    A developmental and training study of children's ability to find safe routes across the road

    British Journal of Developmental Psychology

    (1993)
  • M.L Connelly et al.

    Child pedestrian's judgements of safe crossing gaps at three different vehicle approach speeds: a preliminary study

    Education and Treatment of Children

    (1996)
  • J.D Demetre et al.

    Young children's learning on road-crossing simulations

    British Journal of Educational Psychology

    (1993)
  • J.D Demetre et al.

    Errors in young children's decisions about traffic gaps: experiments with roadside simulations

    British Journal of Psychology

    (1992)
  • E.B Ebbesen et al.

    Laboratory and field analyses of decisions involving risk

    Journal of Experimental Psychology: Human Perception and Performance

    (1977)
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    This research was completed by the first two authors as a graduate student research project undertaken as a part of their Master of Social Science degrees.

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